System for controlling tension of films and system for manufacturing a polarizing plate comprising the same

ABSTRACT

A film tension control system according to an embodiment of the present disclosure includes a delamination unit installed on a transfer path of a polarizing plate to delaminate a release film from a polarizing film, the polarizing plate including the polarizing film and the release film attached to one surface of the polarizing film, an inspection unit installed on a transfer path of the polarizing film to inspect if impurities are present in an adhesive layer formed on one surface of the polarizing film, a tension indication unit installed on a movement path of the release film to indicate a degree of tension applied to the release film, a re-lamination unit to re-laminate the release film having passed through the tension indication unit on the adhesive layer of the polarizing film having passed through the inspection unit, and a tension adjustment unit installed on the transfer path of the re-laminated polarizing plate to adjust the tension of the optical film and the release film.

This application is a Reissue of U.S. patent application Ser. No.15/037,590, filed May 18, 2016, U.S. Pat. No. 10,052,830, which is aNational Stage Application of International Application No.PCT/KR2015/002097, filed Mar. 4, 2015, and claims the benefit of KoreanPatent Application No. 10-2014-0106156, filed Aug. 14, 2014, thecontents of which are incorporated herein by reference in their entiretyfor all purposes as if fully set forth below.

TECHNICAL FIELD

The present disclosure relates to a film tension control system and asystem for manufacturing a polarizing plate comprising the same, andmore particularly, to a film tension control system for suitablymaintaining the tension of a polarizing film and a release film in theprocess of re-lamination after delaminating the release film from onesurface of the polarizing film, and a system for manufacturing apolarizing plate comprising the same.

This application claims priority to Korean Patent Application No.10-2014-0106156 filed on Aug. 14, 2014 with the Korean IntellectualProperty Office, the disclosure of which is herein incorporated byreference in its entirety.

BACKGROUND ART

A polarizing plate may be generally manufactured by laminating a triacetate cellulose (TAC) film on both surfaces of a poly vinyl alcohol(PVA) film, attaching a protection film to the TAC film surface on anyone surface to make a multi-structured polarizing film, and attaching arelease film using an adhesive to a surface opposite to a surface wherethe protection film is formed.

Referring to FIG. 1, a multi-structured polarizing plate made by astacking process as described above is conveyed after being cut to anoptimum length through a cutting process, and before conveying thepolarizing plate, inspection is performed to determine if impuritieshave been introduced into an adhesive layer.

That is, impurities may be introduced into an adhesive during anadhesive applying (coating) operation in the manufacture of thepolarizing plate, and in this case, a spot defect may occur, and todetect the defect, an amount of light bleeding is measured with the samepolarizing plate in a crossed position.

However, at this inspection stage, the release film attached to onesurface of the polarizing film may reduce a degree of polarization oflight, resulting in inaccurate inspection for impurities that may havebeen introduced.

DISCLOSURE Technical Problem

The present disclosure is designed to solve the above problem, and anobject of the present disclosure is to improve accuracy of inspectionfor impurities that may have been introduced into an adhesive layerformed on one surface of a polarizing film, and to improve the qualityof a manufactured polarizing plate by suitably maintaining the tensionof a polarizing film and a release film in the re-lamination of the twofilms that have been delaminated from each other.

The other objects and advantages of the present disclosure will beapparent from the following description and the exemplary embodiments ofthe present disclosure. Also, it will be readily understood that theobjects and advantages of the present disclosure are realized by themeans and combinations thereof set forth in the appended claims.

Technical Solution

To achieve the above objects, a film tension control system according toone embodiment of the present disclosure includes a delamination unitinstalled on a transfer path of a polarizing plate to delaminate arelease film from a polarizing film, the polarizing plate including thepolarizing film and the release film attached to one surface of thepolarizing film, an inspection unit installed on a transfer path of thepolarizing film to inspect if impurities are present in an adhesivelayer formed on one surface of the polarizing film, a tension indicationunit installed on a movement path of the release film to indicate adegree of tension applied to the release film, a re-lamination unit tore-laminate the release film having passed through the tensionindication unit on the adhesive layer of the polarizing film havingpassed through the inspection unit, and a tension adjustment unitinstalled on the transfer path of the re-laminated polarizing plate toadjust the tension of the optical film and the release film.

The film tension control system may include a plurality of guide rollersinstalled on the transfer paths of the polarizing film, the releasefilm, and the polarizing plate to guide the transfer of each element.

The delamination unit may include a pair of rollers disposed at oppositesides with the polarizing plate sandwich between.

Of the pair of rollers, a roller coming into contact with the releasefilm may adsorb the release film to delaminate the release film from thepolarizing film.

The inspection unit may include a light source and a vision cameradisposed at opposite sides with the polarizing film sandwiched between,and a cross filter disposed between the light source and the visioncamera.

The tension indication unit may be a dancer roller installed to move upwhen the tension of the release film increases and to move down when thetension of the release film reduces.

The re-lamination unit may be implemented in a form of a pair of rollersdisposed at opposite sides with the polarizing film and the release filmsandwiched between.

The tension adjustment unit may include an action roller to guide thetransfer of the re-laminated polarizing plate, and an actuator connectedto the action roller to move up and down the action roller.

The film tension control system may enable interoperation of theindication unit and the tension adjustment unit.

To achieve the above objects, a system for manufacturing a polarizingfilm according to one embodiment of the present disclosure isimplemented to include the film tension control system.

Advantageous Effects

According to one aspect of the present disclosure, in the inspection todetermine if impurities have been introduced into an adhesive layerformed on one surface of a polarizing film, its accuracy may beincreased.

According to another aspect of the present disclosure, in there-lamination of a polarizing film and a release film delaminated toperform inspection for impurities that may have been introduced, thequality of a manufactured polarizing plate may be improved by suitablymaintaining the tension of the two films.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawing illustrates a preferred embodiment of thepresent disclosure and together with the foregoing disclosure, serves toprovide further understanding of the technical spirit of the presentdisclosure, and thus, the present disclosure is not construed as beinglimited to the drawing.

FIG. 1 is a block diagram illustrating a system for manufacturing apolarizing plate according to a related art.

FIG. 2 is a block diagram illustrating a film tension control systemaccording to one embodiment of the present disclosure and a system formanufacturing a polarizing plate comprising the same.

FIG. 3 is a diagram illustrating an exemplary implementation of apolarizing plate applied to the present disclosure.

FIG. 4 is a diagram illustrating an exemplary implementation of a filmtension control system according to one embodiment of the presentdisclosure.

FIG. 5 is a diagram illustrating a tension relationship between twodelaminated films.

FIGS. 6 through 9 are diagrams illustrating a movement of a tensionindication unit based on a tension level of a polarizing film and amovement of a tension adjustment unit in response thereto.

FIG. 10 is a block diagram illustrating a part of a tension controlsystem for a polarizing film according to another embodiment of thepresent disclosure.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present disclosure will be described in detail. Priorto the description, it should be understood that the terms used in thespecification and the appended claims should not be construed as limitedto general and dictionary meanings, but interpreted based on themeanings and concepts corresponding to technical aspects of the presentdisclosure on the basis of the principle that the inventor is allowed todefine terms appropriately for the best explanation. Therefore, thedescription proposed herein is just a preferable example for the purposeof illustrations only, not intended to limit the scope of thedisclosure, so it should be understood that other equivalents andmodifications could be made thereto without departing from the spiritand scope of the disclosure.

The entire architecture of a system for manufacturing a polarizing plateaccording to one embodiment of the present disclosure and a film tensioncontrol system therefor is described with reference to FIG. 2.

FIG. 2 is a block diagram illustrating a film tension control systemaccording to one embodiment of the present disclosure and a system formanufacturing a polarizing plate comprising the same.

Referring to FIG. 2, the system for manufacturing a polarizing plateaccording to one embodiment of the present disclosure is implemented toinclude a lamination unit 10, a film tension control system 20, acutting unit 30 and a conveyance unit 40, and the film tension controlsystem 20 is implemented to include a delamination unit 21, aninspection unit 22, a tension indication unit 23, a re-lamination unit24, and a tension adjustment unit 25.

The lamination unit 10 stacks films on top of each other, including apoly vinyl alcohol (PVA) film, a tri acetate cellulose (TAC) film, aprotection film, and a release film, to manufacture a completepolarizing plate, and provides and laminates each film using a roll toroll technique to form a multi-layer polarizing plate.

The film tension control system 20 is configured to, in the polarizingplate formed by laminating the plurality of films through the laminationunit 10, delaminate the polarizing plate into two to inspect ifimpurities have been introduced into an adhesive layer, and re-laminatethem.

That is, the delamination unit 21 acts to delaminate the polarizingplate composed of the plurality of film layers into two (the polarizingfilm and the release film), and the inspection unit 22 acts to, of thetwo delaminated films, inspect if impurities are present in thepolarizing film with an adhesive layer.

Also, the tension indication unit 23 acts to indicate a degree oftension applied to the release film by moving based on the degree oftension, and the re-lamination unit 24 acts to re-laminate thedelaminated polarizing film and release film, and the tension adjustmentunit 25 acts to suitably adjust the tension of the polarizing film andthe release film based on the degree of tension of the release filmbeing indicated through the tension indication unit 23.

The cutting unit 30 is configured to cut, to an optimum size for adesired purpose of an application device to be used, the polarizingplate having undergone the inspection to determine if impurities havebeen introduced and re-lamination through the film tension controlsystem 20, and the conveyance unit 40 is configured to convey the cutpolarizing plate to transport it outside a processing line.

Next, an exemplary implementation of the film tension control systemaccording to one embodiment of the present disclosure is described inmore detail with reference to FIGS. 3 and 4.

FIG. 3 is a diagram illustrating an exemplary implementation of thepolarizing plate applied to the present disclosure, and FIG. 4 is adiagram illustrating an exemplary implementation of the film tensioncontrol system according to one embodiment of the present disclosure.

Referring first to FIG. 3, the polarizing plate (F) applied to thepresent disclosure may be implemented in a structure in which a TAC filmis stacked on both surfaces of a PVA film, and a protection film isstacked on top thereof on one side and a release film (F2) on the otherside opposite thereto with an adhesive layer that is placed inside.

In the description of the present disclosure, the remaining part of thepolarizing plate (F) except the release film (F2) part, that is, a partwith the protection film and the adhesive layer on both surfaces isdefined as a polarizing film (F1).

Referring to FIG. 4, the delamination unit 21 is installed on a transferpath of the polarizing plate (F) to delaminate the release film (F2)from the polarizing film (F1), and may be implemented to include a pairof rollers disposed on the opposite sides of the polarizing plate (F).

In this case, of the pair of rollers, a roller coming into contact withthe release film (F2) may have an adsorption pad to adsorb the releasefilm (F2), or such an adsorption pad may be provided along an outerperipheral surface of the roller, and through the pair of rollers, thepolarizing plate (F) may be delaminated into two pieces.

Of the delaminated polarizing film (F1) and release film (F2) throughthe delamination unit 21, the inspection unit 22 is installed on atransfer path of the polarizing film (F1) to inspect if impurities arepresent in the adhesive layer formed on one surface of the polarizingfilm (F1) (to detect impurities that may have been introduced duringapplying an adhesive on one surface of the polarizing film, causing aspot defect), and may include a light source 22a, a cross filter 22b,and a vision camera 22c.

The light source 22a and the vision camera 22c are disposed at theopposite sides on a movement path of the polarizing film (F1)delaminated from the release film (F2) with the polarizing film (F1)sandwiched between, and the cross filter 22b is disposed between thelight source 22a and the vision camera 22c.

The tension indication unit 23 is installed on a movement path of therelease film (F2) delaminated from the polarizing film (F1), differentfrom the movement path of the polarizing film (F1), and may beimplemented in the form of a dancer roller moving up and down based on amagnitude of tension applied to the release film (F2).

In this case, the dancer roller is installed between a pair of guiderollers (R) which guides the transfer of the release film (F2), andmoves up when the tension applied to the release film (F2) increases andmoves down when the tension reduces.

In this instance, the guide rollers (R) are configured to guide thetransfer of the film, and for stable transfer of the polarizing plate(F), the polarizing film (F1), and the release film (F2), a plurality ofguide rollers may be installed on a transfer path of the film as well asboth sides of the dancer roller.

The re-lamination unit 24 is configured to re-laminate the release film(F2) having passed through the tension indication unit 23 on theadhesive layer of the polarizing film (F1) having passed through theinspection unit 22, and may be implemented in the form of a pair ofrollers disposed on the opposite sides with the polarizing film (F1) andthe release film (F2) sandwiched between.

That is, the polarizing film (F1) and the release film (F2) beingtransferred along different paths after delaminated through thedelamination unit 21 are put together again through the pair of rollers.

Subsequently, the tension adjustment unit 25 is installed on thetransfer path of the polarizing plate (F) being transferred through there-lamination unit 24 to adjust the tension of the optical film (F1) andthe release film (F2), and may be implemented to include an actionroller to adjust the tension of the optical film (F1) and the releasefilm (F2) through up and down movements while guiding the movement ofthe re-laminated polarizing plate (F).

That is, the tension adjustment unit 25 may be connected to an actuatorfor up and down movements, and a user of the system may adjust thetension of each film (F1,F2) to an optimum level by moving the actionroller based on the degree of tension of each film (F1,F2) detectedthrough the tension indication unit 23.

The tension change aspects of each film (F1, F2) in response to themovement of the dancer roller and the action roller are described inmore detail with reference to FIGS. 5 through 9.

FIG. 5 is a diagram illustrating a tension relationship between the twodelaminated films, and FIGS. 6 through 9 are diagrams illustrating themovement of the tension indication unit based on the tension level ofthe polarizing film and the movement of the tension adjustment unit inresponse thereto.

First, referring to FIG. 5, of the two delaminated films (F1, F2), whenthe tension of the release film (F2) increases, the polarizing film (F1)is drawn by the force along a movement direction of the films (F1, F2,F) (along a direction of an arrow in FIG. 5), and as a consequence, thetension applied to the polarizing film (F1) rather reduces. In turn,when the tension of the release film (F2) reduces, the tension of thepolarizing film (F1) increases.

As described above, the tension applied to the two films (F1, F2) showdifferent aspects of changes because the two films are delaminated, andif this imbalance of tension is not corrected, the polarizing plateobtained by re-laminating the two films (F1, F2) cannot avoid a qualitydeterioration.

Thus, the tension of the two films (F1, F2) should be maintained at anoptimum level using the tension adjustment unit 25 based on the tensionlevel of the release film (F2) detected through the tension indicationunit 23 applied to the present disclosure.

Referring to FIG. 6, it can be seen that the dancer roller has movedfarther down than a reference location representing an optimum tensionlevel of the release film (F2). This implies that the tension of therelease film (F2) is lower than the optimum level, in other words, thetension of the polarizing film (F1) is higher than the optimum level.

Thus, in this case, as shown in FIG. 7, an operation of moving up theaction roller is performed to reduce the tension of the polarizing film(F1) and thereby increase the tension of the release film (F2) with anaim of balanced tension between the two films (F1, F2).

Referring to FIG. 8, it can be seen that the dancer roller has movedfarther up than the reference location representing the optimum tensionlevel of the release film (F2). This implies that the tension of therelease film (F2) is higher than the optimum level, in other words, thetension of the polarizing film (F1) is lower than the optimum level.

Thus, in this case, as shown in FIG. 9, an operation of moving down theaction roller is performed to increase the tension of the polarizingfilm (F2) and thereby increase the tension of the release film (F2) withan aim of balanced tension between the two films (F1, F2).

As described above, the film tension control system according to oneembodiment of the present disclosure and the system for manufacturing apolarizing plate comprising the same may improve the quality of acomplete polarizing plate by achieving a balanced tension between twodelaminated films when delaminating a polarizing plate into two foraccurate inspection for impurities that may have been introduced intothe polarizing film.

Next, the film tension control system according to another embodiment ofthe present disclosure is described with reference to FIG. 10.

FIG. 10 is a block diagram illustrating a part of the film tensioncontrol system according to another embodiment of the presentdisclosure.

The film tension control system according to another embodiment of thepresent disclosure has substantially the same elements as the previousembodiment, except an additional element provided for interoperationbetween the tension indication unit 23 and the tension adjustment unit25. Thus, in the description of the film tension control systemaccording to another embodiment of the present disclosure, anoverlapping description with the previous embodiment is omitted and onlya difference is described below.

Referring to FIG. 10, the film tension control system according toanother embodiment of the present disclosure may further include atension measurement unit 26 and a control unit 27 for interoperationbetween the tension indication unit 23 and the tension adjustment unit25, that is, to enable an automatic operation of the tension adjustmentunit 25 based on the tension level of the release film (F2) indicated bythe tension indication unit 23.

The tension measurement unit 26 detects a location based on up and downmovement of the tension indication unit 23, generates informationcorresponding thereto, and transmits it to the control unit 27. Thetension measurement unit 26 may be a sensor mechanically connected tothe tension indication unit 23, but may measure the tension usingoptical sensing without a mechanical connection.

The control unit 27 compares the information associated with thelocation of the tension measurement unit 26 received from the tensionmeasurement unit 26 to a prestored reference value, and outputs acontrol signal for controlling the movement of the tension adjustmentunit 25 based on a result of the comparison, and the tension adjustmentunit 25 receiving the outputted control signal works to adjust thetension of each film (F1, F2) in response to the control signal.

As described above, the film tension control system according to anotherembodiment of the present disclosure is configured to enableinteroperation between the tension indication unit 23 and the tensionadjustment unit 25 to automatically adjust the tension of the films (F1,F2) in the process of re-lamination after delamination of the films (F1,F2), thereby ensuring a high quality of the complete polarizing film (F)and improving efficiency in the manufacturing process.

While the present disclosure has been hereinabove described inconnection with only a limited number of embodiments and drawings, thepresent disclosure is not limited thereto and it should be understoodthat various changes and modifications may be made by an ordinary personskilled in the art within the spirit and scope of the disclosure and theappended claims and their equivalents.

What is claimed is:
 1. A film tension control system comprising: adelamination unit installed on a transfer path of a polarizing plate todelaminate a release film from a polarizing film, the polarizing platecomprising the polarizing film and the release film attached to anadhesive layer formed on one surface of the polarizing film; aninspection unit installed next to the delamination unit on a transferpath of the polarizing film to inspect if impurities are present in theadhesive layer formed on one surface of the polarizing film havingpassed through the delamination unit; a tension indication unitinstalled on a movement path of the release film to indicate a degree oftension applied to the release film; a re-lamination unit to re-laminatethe release film having passed through the tension indication unit onthe adhesive layer of the polarizing film having passed through theinspection unit; and a tension adjustment unit installed next to there-lamination unit on a transfer path of the re-laminated polarizingplate to adjust the tension of the optical polarizing film and therelease film.
 2. The film tension control system according to claim 1,wherein the film tension control system comprises a plurality of guiderollers installed on the transfer paths of the polarizing film, therelease film, and the polarizing plate to guide the transfer of eachelement.
 3. The film tension control system according to claim 1,wherein the delamination unit comprises a pair of rollers disposed atopposite sides with the polarizing plate sandwich between.
 4. The filmtension control system according to claim 3, wherein one of the pair ofrollers coming into contact with the release film adsorbs the releasefilm to delaminate the release film from the polarizing film.
 5. Thefilm tension control system according to claim 1, wherein the inspectionunit comprises a light source and a vision camera disposed at oppositesides with the polarizing film sandwiched between, and a cross filterdisposed between the light source and the vision camera.
 6. The filmtension control system according to claim 1, wherein the tensionindication unit is a dancer roller installed to move up when the tensionof the release film increases and to move down when the tension of therelease film reduces.
 7. The film tension control system according toclaim 1, wherein the re-lamination unit is implemented in a form of apair of rollers disposed at opposite sides with the polarizing film andthe release film sandwiched between.
 8. The film tension control systemaccording to claim 1, wherein the tension adjustment unit comprises: anaction roller to guide the transfer of the re-laminated polarizingplate; and an actuator connected to the action roller to move up anddown the action roller.
 9. The film tension control system according toclaim 1, wherein the film tension control system enables interoperationof the indication unit and the tension adjustment unit.
 10. A system formanufacturing a polarizing film, comprising a film tension controlsystem according to claim
 1. 11. A system for manufacturing a polarizingfilm, comprising a film tension control system according to claim
 2. 12.A system for manufacturing a polarizing film, comprising a film tensioncontrol system according to claim
 3. 13. A system for manufacturing apolarizing film, comprising a film tension control system according toclaim
 4. 14. A system for manufacturing a polarizing film, comprising afilm tension control system according to claim
 5. 15. A system formanufacturing a polarizing film, comprising a film tension controlsystem according to claim
 6. 16. A system for manufacturing a polarizingfilm, comprising a film tension control system according to claim
 7. 17.A system for manufacturing a polarizing film, comprising a film tensioncontrol system according to claim
 8. 18. A system for manufacturing apolarizing film, comprising a film tension control system according toclaim
 9. 19. A method of manufacturing a polarizing plate, the methodcomprises: providing a polarizing plate comprising a polarizing filmlaminated with a release film using a pressure sensitive adhesive layer,delaminating the release film from the pressure sensitive adhesive layeron the polarizing film by a delamination unit installed on a transferpath of the polarizing plate, inspecting the pressure sensitive adhesivelayer disposed on the polarizing film having passed through thedelamination unit for impurities by an inspection unit installed next tothe delamination unit on a transfer path of the polarizing film,indicating a degree of tension applied to the release film by using atension indication unit installed on a movement path of the releasefilm, re-laminating the release film having passed through the tensionindication unit on the pressure sensitive adhesive layer on thepolarizing film having passed through the inspection unit by are-lamination unit to form a re-laminated polarizing plate, adjustingthe tension of the multilayered polarizing film and the release film bya tension adjustment unit installed next to the re-lamination unit on atransfer path of the re-laminated polarizing plate, cutting thepolarizing plate, and conveying the polarizing plate cut to outside aprocessing line.
 20. A method of inspecting a polarizing plate, themethod comprises: providing a polarizing plate comprising a polarizingfilm laminated with a release film using a pressure sensitive adhesivelayer, delaminating the release film from the pressure sensitiveadhesive layer on the polarizing film by a delamination unit installedon a transfer path of the polarizing plate, inspecting the pressuresensitive adhesive layer disposed on the polarizing film having passedthrough the delamination unit for impurities by an inspection unitinstalled next to the delamination unit on a transfer path of thepolarizing film, indicating a degree of tension applied to the releasefilm by using a tension indication unit installed on a movement path ofthe release film, re-laminating the release film having passed throughthe tension indication unit on the pressure sensitive adhesive layer onthe polarizing film having passed through the inspection unit by are-lamination unit to form a re-laminated polarizing plate, andadjusting the tension of the multilayered polarizing film and therelease film by a tension adjustment unit installed next to there-lamination unit on a transfer path of the re-laminated polarizingplate.